The present invention pertains to round balers with a twine wrapping apparatus that includes an improved twine cutting apparatus. More particularly, the present invention pertains to an improved twine cutting apparatus including self-aligning twine cutting knives.
Typical round balers (also referred to simply as a xe2x80x9cbalersxe2x80x9d), such as disclosed in U.S. Pat. No. 6,209,450 to Naaktgeboren et al., are agricultural machines that pick up a cut crop material from the ground and form it into a compacted round bale in a bale-forming chamber. When the bale has been sufficiently compacted to a desired density or a desired size depending on the baler construction, appropriate sensors, such as a bale density or bale size sensor, send signals to a controller. The controller subsequently sends a signal to an operator""s panel to stop forward motion of the baler so that a bale wrapping operation can be performed. In this way, the formed bale is wrapped with netting or twine to produce a completed, wrapped bale.
As is conventionally known, the wrapping operation is performed by a bale wrapping mechanism controlled by a bale wrapping algorithm preprogrammed into a controller (i.e., microprocessor) that is part of the baler. The bale wrapping mechanism has two twine wrapping tubes/arms, wherein each tube/arm dispenses a single strand of twine. When a wrap cycle is initiated, the end of each twine strand dangles from its twine tube and is caught by the bale as the bale continues to rotate in the bale forming chamber. As the bale rotates, the caught ends of the twine strands rotate with the bale and twine is wrapped around the bale. At the end of a wrap cycle, a tying operation is performed as is generally known. Before the completed, wrapped bale can be expelled from the baler, the twine strands must be cut.
The bale wrapping mechanism includes a knife assembly having a cutting edge, and a shear bar that cooperates with the cutting edge of the knife assembly. The knife assembly generally includes two knives (i.e., a right knife and a left knife), each with its own cutting edge. At the start of a wrap cycle, the twine strands are positioned between the knife assembly and the shear bar, and the knife assembly and shear bar are spaced apart so that the twine strands can move freely between the knife assembly and the shear bar. At the end of the wrap cycle (i.e., after the twine ends have been secured by tying), the knife assembly moves by translation or rotation to engage the shear bar, so that the cutting edge of each knife of the knife assembly pinches a respective one of the twine strands against the shear bar, and the twine strands are cut.
One drawback of the prior art bale wrapping mechanism is that the knife assembly has to be properly aligned with the shear bar in order to ensure proper severing of the twine strands by the bale wrapping mechanism. As is generally known, proper alignment may require one or more of the following parameters to be adjusted: (1) position of the knife assembly and cutting edge, (2) position of the shear bar, (3) position of the left knife relative to the position of the right knife, and (4) force with which the cutting edge of the knife assembly strikes the shear bar. In addition, these alignment adjustments become more difficult and complex when considering the new round balers that include a bale wrapping apparatus that has four twine wrapping tubes/arms, wherein each tube/arm dispenses a single strand of twine. The advantage of a round baler having four twine strands provided for wrapping over the conventional two twine strands is that four strands permit completion of the wrapping operation in less time than can be achieved when only two strands are available.
For these reasons, it would be advantageous to have a bale wrapping mechanism that includes a knife assembly having self aligning knives whereby the self aligning knives automatically adjust the orientation of the cutting edge of each knife to the shear bar to ensure reliable severing of all of the twine strands.
The present invention endeavors to provide a round baler with an improved bale wrapping apparatus with a knife assembly having self-aligning knives whereby the self-aligning knives automatically adjust the orientation of the cutting edge of each knife to the shear bar to ensure reliable cutting of all of the twine strands.
Accordingly, an object of the present invention is to overcome the disadvantages of prior art round balers.
Another object of the present invention is to provide a round baler with improved bale wrapping apparatus having a knife assembly with self aligning knives that is practical and cost effective to manufacture.
A still further object of the present invention is to provide a round baler with improved bale wrapping apparatus having a knife assembly with self-aligning knives that is durable and that reliably cuts all of the twine strands.
Yet another object of the present invention is to provide a round baler with improved bale wrapping apparatus having a knife assembly with self-aligning knives that is easy to maintain.
In accordance with the above objectives, one embodiment of the present invention provides a round baler, including a housing with a bale chamber defined therein, and a bale wrapping apparatus, disposed in the housing adjacent the bale chamber to wrap a rotating bale formed in the chamber, the bale wrapping apparatus characterized by: (a) two twine supply rolls rotatingly connected to the housing and defining two twine strands; (b) two twine dispensing arms, each dispensing arm presenting one of the two twine strands; (c) a first shear bar connected to the housing; and (d) a first knife assembly rotatingly connected to the housing by an elongated bar and rotation from a first position to a second cutting position in contact with the first shear bar, wherein each twin dispensing arm is movable from a first position presenting a strand to the bale to a second position wherein the twine strand extends transversely between the first shear bar and the first knife assembly, the first knife assembly comprising: (i) a mounting assembly comprising a mounting member having two protruding posts; (ii) a knife having two slots formed therein and a cutting edge, the knife mounted on the mounting member so that each protruding post extends through one of the slots; and (iii) a biasing member disposed on each post so as to bias the knife toward the mounting member while permitting the knife to move relative to the mounting member when the cutting edge of the knife rotates toward the second cutting position in contact with the first shear bar.
In accordance with a second embodiment, each biasing member is a spring.
In accordance with a third embodiment, each biasing member is a washer or grommet made of elastically compressible material.
In accordance with a fourth embodiment, the first embodiment further comprises: (e) two additional twine supply rolls rotatingly connected to the housing and defining two additional twine strands; (f) two additional twine dispensing arms, each dispensing arm presenting one of the two additional twine strands; (g) a second shear bar connected to the housing; and (h) a second knife assembly rotatingly connected to the housing by the elongated bar and rotatable from a first position to a second cutting position in contact with the second shear bar, wherein each additional twin dispensing arm is movable from a first position presenting a twine strand to the bale to a second position wherein the additional twine strand extends transversely between the second shear bar and the second knife assembly, the second knife assembly comprising: (i) a mounting assembly comprising a mounting member having two protruding posts; (ii) a knife having two slots formed therein and a cutting edge, the knife mounted on the mounting member so that each protruding post extends through one of the slots; and (iii) a biasing member disposed on each post so as to bias the knife toward the mounting member while permitting the knife to move relative to the mounting member when the cutting edge of the knife rotates toward the second cutting position in contact with the second shear bar.
In accordance with a fifth embodiment, the fourth embodiment is further modified so that each biasing member is a spring.
In accordance with a sixth embodiment, the fourth embodiment is further modified so that each biasing member is a washer or grommet made of elastically compressible material.
In accordance with a seventh embodiment of the present invention, there is provided an assembly for cutting multiple twin strands comprising: (a) a shear bar; (b) a rotatable bar; (c) a mounting assembly comprising a mounting member having two protruding posts, the mounting assembly being attached to the rotatable bar; (d) a knife having two slots formed therein and a cutting edge, the knife mounted on the mounting member so that each protruding post extends through one of the slots; and (e) a biasing member disposed on each post so as to bias the knife toward the mounting member; while permitting the knife to move relative to the mounting member. The cutting edge of the knife is rotatable toward a cutting position in contact with the shear bar. Preferably, each biasing member is a spring, a washer or a grommet made of elastically compressible material.